Improved kinetic rate assay of urinary N-acetyl-beta-D-glucosaminidase with 2-chloro-4-nitrophenyl-N-acetyl-beta-D-glucosaminide as substrate.
We have improved the kinetic rate assay method for determining N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30; NAG) activity in urine with use of the synthetic substrate, 2-chloro-4-nitrophenyl-N-acetyl-beta-D-glucosaminide (CNP-NAG), reported previously (Clin Chem 1988;34:2140-2). To increase the solubility of this substrate, we used crown ether (15-crown-5-ether) and ethylene glycol. In addition, we used for the standard solution NAG from human placenta, with specificity corresponding to that of human urine, so that values obtained with the CNP-NAG method and a p-nitrophenyl-NAG method ("MEI Assay NAG") correlated almost completely (r = 0.995, n = 29). Reference values for urinary NAG activity determined by the CNP-NAG method were established for untimed urine specimens from 674 healthy volunteers. The normal reference interval (mean +/- 2 SD) for NAG: 1.6-15.0 (mean 4.9) U per gram of creatinine.
Makise
J
J
Central Clinical Laboratory, Yokosuka Kyosai Hospital, Kanagawa, Japan.
Saito
E
E
Obuchi
M
M
Kanayama
M
M
Harakawa
K
K
Yoshida
K
K
D000117:Acetylglucosamine / Q000031:analogs & derivatives*; D000118:Acetylglucosaminidase / Q000652:urine*; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003920:Diabetes Mellitus / Q000201:enzymology / Q000652:urine; D005260:Female; D005944:Glucosamine / Q000031:analogs & derivatives*; D006304:Health Status; D006596:Hexosaminidases / Q000652:urine*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010920:Placenta / Q000201:enzymology; D012016:Reference Values
C057414:2-chloro-4-nitrophenyl-N-acetylglucosaminide; D006596:Hexosaminidases; D000118:Acetylglucosaminidase; D005944:Glucosamine; D000117:Acetylglucosamine